I am not much of an OpenGL guy, but are you seeing any issues in using without filling the texture? The Khronos specs does not mention anything specific about requiring to initialize the texture object clCreateFromGLTexture.
These are the requirements though:
The name of a GL 1D, 2D, 3D, 1D array, 2D array, cubemap, rectangle or buffer texture object. The texture object must be a complete texture as per OpenGL rules on texture completeness. The texture format and dimensions defined by OpenGL for the specified miplevel of the texture will be used to create the OpenCL image memory object. Only GL texture objects with an internal format that maps to appropriate image channel order and data type specified in tables 5.5 and 5.6 may be used to create the OpenCL image memory object.